x86: Begin to introduce support for MSR_ARCH_CAPS

... including serialisation/deserialisation logic and unit tests.

There is no current way to configure this MSR correctly for guests.
The toolstack side this logic needs building, which is far easier to
do with it in place.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: e32605b07ef2e01c9d05da9b2d5d7b8f9a5c7c1b
master date: 2020-08-27 12:48:46 +0100

diff --git a/tools/tests/cpu-policy/test-cpu-policy.c b/tools/tests/cpu-policy/test-cpu-policy.c
index 7ba9707236bbc02d89f599a9c2c5adbc6af17a75..0fa209f1ea7c3d18b0393c2a0aa2d2b044aa1c4d 100644 (file)
--- a/tools/tests/cpu-policy/test-cpu-policy.c
+++ b/tools/tests/cpu-policy/test-cpu-policy.c
@@ -374,6 +374,11 @@ static void test_msr_deserialise_failure(void)
             .msr = { .idx = 0xce, .val = ~0ull },
             .rc = -EOVERFLOW,
         },
+        {
+            .name = "truncated val",
+            .msr = { .idx = 0x10a, .val = ~0ull },
+            .rc = -EOVERFLOW,
+        },
     };
 
     printf("Testing MSR deserialise failure:\n");

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index 22f921cc71003c7bb1c356123083faa735a82f66..7d99c0e64c9140da073ef36c36598ae1549ab845 100644 (file)
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -220,8 +220,10 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
         break;
 
     case MSR_ARCH_CAPABILITIES:
-        /* Not implemented yet. */
-        goto gp_fault;
+        if ( !cp->feat.arch_caps )
+            goto gp_fault;
+        *val = mp->arch_caps.raw;
+        break;
 
     case MSR_INTEL_MISC_FEATURES_ENABLES:
         *val = msrs->misc_features_enables.raw;

diff --git a/xen/include/public/arch-x86/cpufeatureset.h b/xen/include/public/arch-x86/cpufeatureset.h
index fe7492a2256c7c032470f2d7deb564ddc0556e54..d06a2fd4c8e2394df7441ece7d5834a0a282d960 100644 (file)
--- a/xen/include/public/arch-x86/cpufeatureset.h
+++ b/xen/include/public/arch-x86/cpufeatureset.h
@@ -267,7 +267,7 @@ XEN_CPUFEATURE(CET_IBT,       9*32+20) /*   CET - Indirect Branch Tracking */
 XEN_CPUFEATURE(IBRSB,         9*32+26) /*A  IBRS and IBPB support (used by Intel) */
 XEN_CPUFEATURE(STIBP,         9*32+27) /*A  STIBP */
 XEN_CPUFEATURE(L1D_FLUSH,     9*32+28) /*S  MSR_FLUSH_CMD and L1D flush. */
-XEN_CPUFEATURE(ARCH_CAPS,     9*32+29) /*   IA32_ARCH_CAPABILITIES MSR */
+XEN_CPUFEATURE(ARCH_CAPS,     9*32+29) /*a  IA32_ARCH_CAPABILITIES MSR */
 XEN_CPUFEATURE(CORE_CAPS,     9*32+30) /*   IA32_CORE_CAPABILITIES MSR */
 XEN_CPUFEATURE(SSBD,          9*32+31) /*A  MSR_SPEC_CTRL.SSBD available */
 

diff --git a/xen/include/xen/lib/x86/msr.h b/xen/include/xen/lib/x86/msr.h
index 203c7133205b90af96b4da1689a8b9f350830f80..48ba4a59c0366ed5963f287610b947cb6018ab92 100644 (file)
--- a/xen/include/xen/lib/x86/msr.h
+++ b/xen/include/xen/lib/x86/msr.h
@@ -3,7 +3,7 @@
 #define XEN_LIB_X86_MSR_H
 
 /* Maximum number of MSRs written when serialising msr_policy. */
-#define MSR_MAX_SERIALISED_ENTRIES 1
+#define MSR_MAX_SERIALISED_ENTRIES 2
 
 /* MSR policy object for shared per-domain MSRs */
 struct msr_policy
@@ -23,6 +23,28 @@ struct msr_policy
             bool cpuid_faulting:1;
         };
     } platform_info;
+
+    /*
+     * 0x0000010a - MSR_ARCH_CAPABILITIES
+     *
+     * This is an Intel-only MSR, which provides miscellaneous enumeration,
+     * including those which indicate that microarchitectrual sidechannels are
+     * fixed in hardware.
+     */
+    union {
+        uint32_t raw;
+        struct {
+            bool rdcl_no:1;
+            bool ibrs_all:1;
+            bool rsba:1;
+            bool skip_l1dfl:1;
+            bool ssb_no:1;
+            bool mds_no:1;
+            bool if_pschange_mc_no:1;
+            bool tsx_ctrl:1;
+            bool taa_no:1;
+        };
+    } arch_caps;
 };
 
 #ifdef __XEN__

diff --git a/xen/lib/x86/msr.c b/xen/lib/x86/msr.c
index 171abf700868697da1d1eccf7d9985e63b1fb5ad..7d71e92a380adb7b5aba0dd85aeb16bd47b9dc5e 100644 (file)
--- a/xen/lib/x86/msr.c
+++ b/xen/lib/x86/msr.c
@@ -39,6 +39,7 @@ int x86_msr_copy_to_buffer(const struct msr_policy *p,
     })
 
     COPY_MSR(MSR_INTEL_PLATFORM_INFO, p->platform_info.raw);
+    COPY_MSR(MSR_ARCH_CAPABILITIES,   p->arch_caps.raw);
 
 #undef COPY_MSR
 
@@ -99,6 +100,7 @@ int x86_msr_copy_from_buffer(struct msr_policy *p,
 })
 
         case MSR_INTEL_PLATFORM_INFO: ASSIGN(platform_info.raw); break;
+        case MSR_ARCH_CAPABILITIES:   ASSIGN(arch_caps.raw);     break;
 
 #undef ASSIGN